Today, multi-station presses, i. e. arrangements of at least two presses arranged in succession, in such a way that workpieces worked on by the first of the presses may be handed over to the second press (directly or employing an intermediate station) are widely used in a variety of applications such as e. g. sheet forming for the production of car bodies. In the following, “multi station press” is understood to include tandem presses, press lines, etc.
Usually, the handing over of the work pieces from a press station to the next one is effected by automatic handling devices. The throughput of a multi station press is not only defined by the speed of the press stations (i. e. strokes per minute) but also by the efficiency of the deposition and removal of workpieces and the transport of the workpieces between the presses. Technically, a large number of different systems for transporting workpieces from station to station are available, having different kinematics involving e. g. linear and/or swivel axes. An example out of many is described in WO 2005/051563 A1 (Güde Group AG). Choosing the appropriate system, in principle very high transport speeds are achievable.
However, todays versatile and fast transport devices often provide much freedom in choosing the trajectory for transporting the workpiece from one station to the next one. In the following, the term “trajectory” is understood to be the path of an object through space as a function of time. It does not only include the geometry of the path, but also the position of the object along the path as a function of time. The trajectories discussed in this document are closed, i. e. the same path is usually ran through repeatedly.
The freedom in chasing the trajectory allows for optimizing the operation of the multi-station press. However, it is not a simple task to define the trajectory such that a high or even optimum throughput of the whole system is achieved. Either the user is provided with limited possibilities of influencing the trajectory, which can mean that the optimum trajectory cannot be generated in any case, or the parameters to be defined are so many that parameterizing the trajectory amounts to a complex and lengthy task which can only be handled by very experienced operators and which involves a lot of trial and error.